The Forster Co-Ax Case and Cartridge Concentricity Gauge with Dial gives the reloader the ability to measure three critical dimensions: neck wall thickness, case neck concentricity and bullet run-out. Measurements are in increments of .001". The case and cartridge inspector checks both the bullet and case alignment in relation to the centerline or axis of the entire case. The use of Forster Case Trimmer Pilots to hold the case are required for use and are sold separately. Accuracy: .001" over 1/2" of travel Notes: Must use Forster Case Trimmer Pilots (not included)